Compress images without changing their format

No. There is no upload endpoint to send them to. The page loads once, and from then on every step — reading the file, decoding it, re-encoding it — happens on your device using your browser’s own image codecs.

Analytics records that the tool was opened, never what you put into it, and a Content Security Policy allows no upload destination at all.

It encodes the image several times at different quality settings and keeps the best one that fits under your budget — a binary search, typically five to eight encodes per image. That is why it takes a moment longer than the slider.

If no quality setting gets under the target, the row says the target was not reached rather than handing you a file over the limit. You can optionally let it shrink the image as well, which is off by default because a smaller picture is not what most people mean by compression.

Not by itself. Compression changes how the pixels are stored, not how many there are. If you also want smaller dimensions, set a width or height under the advanced settings and both will happen in one pass.

Browsers can decode GIF but cannot write it, so there is no way to return a compressed GIF. WebP is the closest honest substitute — it keeps transparency, supports animation, and is usually far smaller.

The tool tells you which files this affects before you start, rather than quietly changing your file type.

Individual files are capped at 25 MB and batches at 50 images, to keep memory use sane on phones and older laptops. Because the work is local, there is no server-side limit beyond what your own device can handle.

Yes. Re-encoding through the browser’s canvas discards metadata as a side effect, so GPS coordinates, camera details and timestamps are not carried into the output. That is worth knowing in both directions — it is good for privacy, but if you need the EXIF preserved, this is not the right tool.